Are electric horses really bigger?

[Caroute Motor]

Caroute. I am a potential client of your products. I am looking at electric outboards above the typical trolling motors and find torqeedo too pricey.

Whether its language barrier, marketing person trying to explain engineering - you are hurting your case. When you start talking about the efficiency of combustion engine affecting how effective the horsepowers are you lose all credibility.
Equally you tout 65% efficiency for your motor while totally messing inputs and outputs.
If the 65% is for your electric motor its pathetic. If its accounting for motor and controller losses and propeller losses its pretty good. Right now we have to guess. Either way to suggest that gas motor would be 30% efficient from engine shaft (that is where the hp is measured btw. Not battery draw like your marketing numbers) to propulsion is an inaccurate blanket statement. Gas engine can have a well matched prop too...

Thanks for your advice. We will changing our adverting words like"equivalents to which HP gas motor". I think we should say the thrust our motor can achive. We will change soon.
Here is 160LB 48V testing report for your reference. It's testing from the electric motor shaft. Propeller size is according the electric motor to design. The electric motor inside IC is doing power management to make sure PRM, Torque, propeller's thrust in a good condition.

 

[gonzo]

That chart has a lot of wrong values. For example, it says that at 50.00V and 60.00A it is using 2500W instead of 3000W. At 5.00V and 6.00A it claims 250.0W instead of 30W. Using the torque/rpm curve, it shows that at 10.50N.m and 2200RPM it uses 2200W, but the formula for torque/rpm calculates that it is producing 2410W; that is more than goes in.

 

[Caroute Motor]

That chart has a lot of wrong values. For example, it says that at 50.00V and 60.00A it is using 2500W instead of 3000W. At 5.00V and 6.00A it claims 250.0W instead of 30W. Using the torque/rpm curve, it shows that at 10.50N.m and 2200RPM it uses 2200W, but the formula for torque/rpm calculates that it is producing 2410W; that is more than goes in.

It's just a testing curve. And you didn't see clearly. There is no 50V or 60A.
2240RPM is unload condition. Testing also test the overload condition, so there is 2410W testing through 48V and 50.14A. If you are a electric motor engineer, we will know this motor work perfect through this curve. Thank you for your interesting again.

 

[daiquiri]

What are P1 and P2 in that graph?

 

[Caroute Motor]

What are P1 and P2 in that graph?

P1: Input Power (Voltage*Current)
P2: Motor Shaft Output Power (Test machine testing)

 

[Caroute Motor]

Your argument seems to ignore that gearboxes are very normal and only consume a few percent. Comparing a direct drive electric with direct drive combustion is a false dilemma.

Also you need to understand the power curve required by a propeller. As it increases in speed it needs exponentially more power. Therefore if the engine struggles with it at low rpm it has no chance of even reaching moderate rpm. Even if you gave it a boost somehow to reach higher rpm, it would be significantly more overloaded there not less loaded. With a certain amount of extra rpm, you might get 4 times the available engine power, but the prop might need 20 times the power as its requirement for power rises much more sharply than an engine power curve.

Right, propeller don't need top PRM and Torque to keep large thrust all the time. There is a power curve, our electric boat inside IC will adjust the output power to make sure the propeller thrust in a best condition. Why we say that our motor can achieves 65% efficiency. The output power is adjust according to our curve, not all the time in top power. In this way, we can save more energy which the propeller doesn't need, and also can potect the electric system not too hot.

 

[DennisRB]

My system also has a similar device to match power output to exactly match my props power curve depending on the vessels required speed.

Its called the throttle cable.

 

[gonzo]

I was refering to P1. Power=V*I. The numbers in the graph don't match the proper calculations. I work on battery/energy storage research, and this is a daily type of calculation.

 

[daiquiri]

I was refering to P1. Power=V*I. The numbers in the graph don't match the proper calculations. I work on battery/energy storage research, and this is a daily type of calculation.

I agree, the graph is made in a confusing way. The scales of V, I, P1 and P2 do not match each other, so it becomes difficult to manually control the resulting curves. That is what has made me ask about the meaning of P1 and P2. Just like you, I am also reading that 50V x 60A = 2500W, which is clearly wrong.

 

[gonzo]

I think that is the graph of a snake oil salesman's pitch. Having the y-axis on the right being different from the left would only work if there were two curves generated for comparison. However, if the curves correspond to P1, P2, etc according to color, all the values are wrong.

 

[daiquiri]

However, if the curves correspond to P1, P2, etc according to color, all the values are wrong.

The values are not necessarily wrong (unless you have checked the numbers), but using different axis scales for the same quantities (P1,P2) is. It makes a double-checking by third parties more difficult. This is not how scientifically valid graphs should be presented.

 

[gonzo]

I mean that if we calculate power by the values on the left scales, the results are a different value than what the power scale shows. It indicates that the motor produces more power than the input.

 

[Caroute Motor]

The values are not necessarily wrong (unless you have checked the numbers), but using different axis scales for the same quantities (P1,P2) is. It makes a double-checking by third parties more difficult. This is not how scientifically valid graphs should be presented.

It's just a electirc brushless trolling motor's performance from unload conditon power to overload condition power. Our enginneer record the Votage, Currents, Motor Shaft Output Power P2 , RPM, Torque. The P1 is counting from Votage*Currents. Efficiency is just P2/P1. We use this for our enignneer to check whether the motor can match our propeller curve. Propeller is another curve. And the unload condition votlage 48.24V, Currents 2.55A. And the overload condition voltage 47.16V, currents 57.25A. So there is no 50V or 60A. Rated power is 2150W, so the overload testing should be proper range.

Yes, it's just a self-testing results for adjusting the trolling motor. It's not third party. But we can sure that all results are truth.

 

[gonzo]

Your graph shows 50V and 60A on the left scale. Either the numbers and calculations are wrong, or the graph is wrong. If you have an engineer doing this, he needs to pay more attention. Excell will generate proper graphs if you input the data. It only takes a few minutes to do.

 

[Caroute Motor]

I mean that if we calculate power by the values on the left scales, the results are a different value than what the power scale shows. It indicates that the motor produces more power than the input.

Sorry that I don't understand. The Max P1 is 2699.91W in overload condition. and the max P2 is 1755W, but it recorded in P1 2409.06W. P1 and P2 are not Synchronization in this graph.